A legal and philosophical slugfest over the fate of a popular oyster farm in the picturesque estuary where Sir Francis Drake landed more than four centuries ago is winding toward a final decision, and not even the National Academy of Sciences can resolve the dispute.

A team of academy scientists could not determine Thursday whether the popular Drakes Bay Oyster Co. is harming the historic waterway along the Point Reyes National Seashore.

"The basic problem is a lack of data," said Thomas Malone, the chairman of the committee of six scientists and one lawyer who reviewed the science in a National Park Service environmental review. "There were (in several cases) other conclusions they could have reached given the information at hand."

The issue is huge in rural west Marin County, and not just because many people consider the oysters from Drakes Bay a delicacy.

The vast coastal area is a haven for cattle ranchers, sheep herders and organic farmers who live and work next to, and in some cases within, National Park Service land. It is a unique relationship - forged years ago in the fight to preserve the land from development - that can also sometimes lead to conflict.

Kevin Lunny, who bought the shellfish operation from Johnson Oyster Co. in 2004, is allowed to harvest oysters in Drakes Bay under a 40-year occupancy agreement reached in 1972. He wants his lease to be renewed when it expires on Nov. 30.

Park service officials, though, have long contended that the oyster operation harms the environment. Their draft environmental impact statement in 2011 concluded, in essence, that the impacts on water, wildlife, wetlands and plants are so great that the oyster company should be kicked out.

Setback to park service

Lunny sees the report, released Thursday by the academy's National Research Council, as a victory. It said there is not enough scientific evidence in the environmental document to conclusively support claims that the shellfish operation causes noise pollution, scares birds and harbor seals, and generally harms shoreline habitat.

"For more than six years, the National Park Service has been telling the people of West Marin that our oyster farm and our workers were harming harbor seals, choking eelgrass and otherwise doing great harm to the environment," Lunny said Thursday in a prepared statement. "We now know that NPS just plain made it up to drive us out of business."

The academy report is yet another blow to the park service, which has been accused by oyster farm proponents led by biological scientist and local resident Corey Goodman of a pattern of misconduct, including the deliberate fudging of data.

In 2009, a panel of scientists concluded that park officials had, in fact, made errors, selectively presented information and misrepresented facts in a series of reports about the shellfish operation. Last year, the Interior Department's office of the solicitor released a report outlining what it termed biased, improper, mistake-ridden work by park scientists, but cleared the researchers of misconduct.

The park's environmental review was required after Sen. Dianne Feinstein, D-Calif., included a rider in an appropriations bill that gave Interior Secretary Ken Salazar discretion to extend the oyster purveyor's lease for 10 years or terminate it when it expires.

More studies needed

The 2011 review concluded that the oyster farm has a major impact on the Drakes Bay "soundscape" and has moderate impacts on wetlands, eelgrass, fauna, harbor seals, birds and the coastal flood zone. Malone said the conclusions were reasonable on their face but impossible to prove without more studies.

"From our perspective they were caught between a rock and a hard place in having to do an environmental assessment with insufficient data to be able to do it well," Malone said.

Neal Desai, the associate director for the National Parks Conservation Association, said the academy report confirmed that the park service used the best available data and came to reasonable conclusions based on that information. The science on oyster farms may be limited, he said, but Salazar's decision this year will be less an evaluation of certainties than an attempt to reconcile potential risks with management goals for the seashore.

"This is a matter of law, policy and science, and the secretary is going to take all of those into consideration," Desai said. "This is ultimately a policy decision. You have to consider whether the risk of environmental damage is consistent with the policies of the park."